A. Field of Invention
This invention pertains generally to cathode ray tube (CRT) alignment and more particularly to the use of a video graphics controller within a host computer to store and transfer correction factor data to and from a CRT video display.
B. Definitions.
Address decoder means a device that interprets address information.
Align means to cause a video image to be adjusted so that distortion characteristics are reduced and the video image that is displayed on the cathode ray tube forms an image that is pleasing to the eye.
Analog decoder means a device that transforms and/or directs an analog signal to a particular channel to produce an analog or digital output signal representative of the analog input signal.
Cathode ray tube means a device that is capable of displaying an image using a magnetically deflected electron beam. A cathode ray tube may include one or more of the following: the tube structure, the phosphor screen, the deflection and control windings, including the yoke, rotation and other coils, and/or the electron guns.
Cathode ray tube (CRT) control circuitry means one or more of the following: horizontal drive circuitry, vertical drive circuitry and/or electric beam gun drive circuitry, and/or coils or windings associated with the cathode ray tube.
Combined video image and correction factor data means data or other signals that contain both video image data and correction factor data, and may contain correction factor address information.
Correction signals means any data or signal, including address information that is used in the process of aligning a video image.
Correction data means correction factor data that does not include correction factor address information.
Correction factor address means an address signal associated with correction data.
Correction factor data comprises the encoded digital bytes or any other form of data or signal that is representative of the distortion characteristics of a cathode ray tube for one or more correction factor parameters. Correction factor data may be generated by a vision system, a gain matrix table, and/or manually generated. Correction factor data may also be in the form of term multipliers and/or parametric data that is used to adjust standardized transformation equations which are representative of the amount of correction needed to align a video signal to counteract various distortion characteristics and may include correction data address information and clock information. Correction factor data may also include correction control data that represents expanded or interpolated data.
Correction factor parameters include various geometry and/or distortion characteristics of the cathode ray tube including horizontal size, raster rotation, vertical size, horizontal center, vertical center, pincushioning, vertical linearity, keystoning, convergence, etc., and various electron gun characteristics of the cathode ray tube including contrast, brightness, luminosity, focus, color balance, color temperature, electron gun cutoff, etc.
Converter means a device for generating an appropriate electronic signal in response to one or more input signals including data inputs. For example, a converter may generate an analog signal from a digital input, decode a data byte, change serial data to parallel format, or the converse of these operations and may include a PWM, a PDM, a DAC, etc.
Display device means any apparatus that produces a video image.
Decoder means a device for generating, transforming, modifying and/or directing a signal or data to a particular location or channel, in response to one or more input signals including data inputs. For example, a decoder may include a pulse width modulator, a pulsedensity modulator, a digital-to-analog converter, an interpolation engine, a lookup table, a processor, screen display chips, a channel routing device, an analog decoder, etc.
Digital data means any data that has a digital nature, including binary data.
Dissimilar data means binary, digital and/or analog signals that are not video image data. Dissimilar data may include audio data, correction factor data, or any other data not specifically related to the video image data.
Distortion characteristics means the type, location and/or amount of distortion as indicated by distortion data.
Distortion data means a signal or data that is representative of the amount of distortion that exists on a cathode ray tube with regard to certain correction factor parameters. For example, distortion data can be measured as a result of misalignment of a video image or improper amplitude or gain of a video signal.
Driver signals means the electrical signals that are used to drive the deflection and control windings, and electron guns of the cathode ray tube.
Dynamically adjusting means to make adjustments that may change during a horizontal and/or vertical scan.
Enable signal means a signal or data that is capable of activating a device.
Host computer means any apparatus having a processor that is used in conjunction with a display device. For example, this may include computers, digital television receivers, set top boxes, etc. that have a processor.
Memory or storage comprises any desired storage medium including, but not limited to, EEPROMS, RAM, EPROMs, PROMs, ROMs, magnetic storage, magnetic floppies, bar codes, serial EEPROMs, flash memory, optical storage magneto-optical storage, DVD, etc., or any improvements of these types of storage or other types of storage, as well as systems for holding information such as LANs, WANs, the internet, the world-wide web, etc.
Parallel data bytes means serial data that has been arranged in parallel format to form bytes.
Processor means a logic device including, but not limited to, state machines, microprocessors, digital signal processors (DSPs), etc.
Retrace time means that duration of time in which the electron beam in a CRT is being moved back to begin its next trace of the video image. Retrace time may occur during either horizontal or vertical retrace.
Serial to parallel converter means any device for changing serial data into parallel data.
Set top box means a processor used in conjunction with a receiver.
Television receiver means a device that receives either a digital or analog television signal and transforms the television signal into a video signal for display on a display device.
Video connector means any device, system or method for transmitting video image data and/or combined video image and/or correction factor data to a cathode ray tube monitor or CRT device, including optical, electrical, RF, magnetic, infrared, etc. connections. The video image data and correction factor data may share the same signal path, or may be transmitted on separate paths. Additionally, the video image data and correction factor data may be transmitted simultaneously or at different times, or may be interleaved or modulated.
Video graphics controller means circuitry associated with a host computer that stores and/or transmits video image data.
Video graphics controller RAM means memory or other storage used for storing video image data and correction factor data in a host computer.
Video image means the displayed image that appears on a display device that is produced in response to a video signal.
Video image data means binary, digital and/or analog signals that are representative of a video image.
C. Description of the Background
Recent developments in-the automated measurement of display device distortion characteristics, in devices such as computer cathode ray tube monitors and television cathode ray tube devices, have made it possible to actively correct display devices for numerous types of distortion. Presently, in cathode ray tube monitors, these corrections are performed within the CRT device by an intelligent digital monitor board using a dedicated processor and memory. As the ability to correct for various types of video distortion characteristics has increased, the memory size and processor speed required to facilitate video alignment has become more expensive and has increased the cost of dynamic adjustment devices. These costs have effectively limited the use of dynamic adjustment techniques to be employed by only the most expensive CRT devices. This has limited the use of dynamic adjustment techniques in most CRT monitors manufactured today.
Therefore, it would be desirable to dynamically adjust cathode ray tube monitors by implementing correction factor data without the dedicated processor and memory presently required within the CRT device. It is against this background and these problems and limitations that the present invention has been developed.
The present invention overcomes the disadvantages and limitations of the prior art by providing an apparatus and method for using a host computer processor and the memory associated with the video graphics controller to dynamically adjust video images on the CRT screen.
The present invention may therefore comprise an apparatus for storing dissimilar digital data with video image data and transmitting the dissimilar digital data and the video image data comprising, a host computer that stores the dissimilar digital data in a memory, and a video connector coupled to the host computer and the display device that transmits both the dissimilar data and video image between the display device and the host computer.
The present invention overcomes the disadvantages and limitations of the prior art by providing a dynamic method of producing an aligned video image on a CRT device by using the processor and memory of a host computer to store and transmit correction factor data representative of the distortion characteristics of a cathode ray tube. Any desired number of individual correction factor parameters, both static and dynamic, may be corrected by the method of this invention to produce the desired aligned, distortion free, video image. The present invention employs the processor and memory residing in the host computer and thus reduces the memory and processing power required within the CRT device. The present invention is capable of extending the benefits of distortion correction to a new class of lower priced display devices. Additionally, the present invention provides a convenient way of transmitting dissimilar data between a monitor and a host computer without the necessity of additional cables.